Radio Signal Quantization for Soft-Bit Fronthaul Bandwidth Limits
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Solution Overview
Problem
The separation of demodulation and decoding functions in radio access networks leads to high data transmission rates for soft bits (LLR) between high and low functions, exceeding the capacity of communication buses, especially in fronthaul networks, and existing compression methods degrade the radio signal quality.
Innovation Solution
A method and device for quantizing radio signal data using a scalar quantization table tailored to the channel coding level, reducing the data size and maintaining signal quality by optimizing quantization tables based on real radio conditions and minimizing channel decoding errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If demodulation and decoding functions are separated into different units, then functional flexibility and management efficiency are improved, but data transmission rate requirements increase beyond communication bus capacity
Solution Approach 1:
The patent extracts only the essential information from soft bits by performing scalar quantization, transforming continuous LLR values into discrete quantized levels. This extraction process removes redundant data while preserving the critical information needed for decoding, thereby reducing the data transmission rate requirement when separating demodulation and decoding functions into different units.
Solution Approach 2:
The patent changes the parameter representation of soft bits by applying scalar quantization with different quantization levels (e.g., 2-bit, 3-bit, 4-bit quantization). By adjusting the quantization parameter, the system can adapt the data rate to match the communication bus capacity while maintaining acceptable decoding performance, thus resolving the contradiction between functional separation and data rate requirements.
2Quantity of substance
If compression methods are applied to reduce data rate, then bandwidth requirements decrease, but radio signal quality deteriorates
Solution Approach 1:
The patent introduces scalar quantization as an intermediary process between demodulation and decoding. Instead of directly compressing soft bits which degrades signal quality, the quantization intermediary transforms continuous LLR values into discrete levels in a controlled manner. This intermediary transformation reduces bandwidth requirements while maintaining better signal quality compared to direct compression methods, as the quantization process preserves the statistical properties and decision information of the original soft bits.
3Measurement precision
If high precision soft bits are transmitted, then channel decoding performance is improved, but communication bus capacity is exceeded
Solution Approach 1:
The patent applies partial quantization action by using a limited number of quantization levels (e.g., 2-bit, 3-bit, or 4-bit quantization) instead of transmitting full-precision soft bits. This partial action approach transmits only the essential information needed for acceptable decoding performance, reducing the data rate to fit within communication bus capacity while maintaining sufficient precision for reliable channel decoding.
Data Source
AI summary
A method for quantizing data representative of a radio signal received by a radio antenna of a mobile network. The method includes: demodulating the radio signal received by the antenna, providing a demodulated signal; scalar quantizing each value of the demodulated signal using a quantization table selected according to a channel coding level used to transmit the radio signal, providing a quantized demodulated signal; and transmitting the quantized demodulated signal to a channel decoding module.